The five-nation BRICS group of major emerging economies is set to more than double in size next year as part of a major expansion that’s expected to boost the bloc’s financial heft as it seeks to provide an alternative model to the Group of Seven.

The grouping, comprising Brazil, Russia, China, India and South Africa, announced Thursday that it has invited six new countries – Argentina, Egypt, Ethiopia, Iran, the United Arab Emirates and Saudi Arabia — to join from Jan. 1 in what is set to be the bloc's biggest enlargement since its formation in 2006.

With the expansion — the first since South Africa joined in 2010 — the group says it will make up 47% of the world's population and account for 36% of global gross domestic product based on purchasing power parity — compared to 30.7% for the G7.